Bubbles

I doubt it's gas supersaturation.....as long as the fins, eyes r not affected. more likely something locally cystic.
Is everything else ok with the aro? like breathing? behaviour? appetite?
get it checked out by your local fish vet. ddx: tumour? trauma? infectious( esp parasitic)??
very interesting n unusual.
Kenny, Vetduck, comments guys?
If i had access to your aro dragon119, i would aspirate whatever is in there( looks more fluidy than air), and send it off to the lab for a culture, cytology. even better, sedate aro and take a chunk off for a biopsy. that should give us a better idea of what it is. obviously we should b doing skin scrapes n gill biopsy too.
i.e off to the vet mate!